The invention relates to a display apparatus in a motor vehicle and to a method for operating a display apparatus.
Such display apparatuses in motor vehicles and methods for operating such display apparatuses are sufficiently well known from the mass production of motor vehicles. FIG. 1 shows a schematic front view of such a display apparatus 10 according to the related art. The display apparatus 10 is usually also called a combination instrument and used for automobiles of the AUDI brand.
The display apparatus 10 comprises a first display element 12 in the form of what is known as a tachometer, which can be used to display values for a speed of an internal combustion engine for driving the automobile. To this end, the display element 12 comprises a value scale 14 with the values for the speed and also a pointer 18 that can be swiveled along the value scale 14 about a swivel axis 16 and that displays the current value of the speed. In the present case, the internal combustion engine is deactivated, which means that the value of the speed is 0.
The display apparatus 10 comprises a second display element 20 in the form of what is known as a speedometer, which can be used to display values for a vehicle speed of the automobile. To this end, the display element 20 comprises a value scale 22 with values for the vehicle speed and also a pointer 26 that can be swiveled along the value scale 22 about a swivel axis 24 in order to display the current value of the vehicle speed. In the present case, the automobile is stationary, which means that the value of the vehicle speed is 0.
The display apparatus 10 also comprises a third display element 28 for displaying values that characterize a filled level of a fuel tank in the automobile. Furthermore, a fourth display element 30 for displaying values for a coolant temperature or a lubricating oil temperature is provided.
In addition, the display apparatus 10 comprises a fifth display element 32 that comprises a liquid crystal screen for displaying different values. One of these values is the current time of day 34 in the present case. Another of these values is a range 36 for which the automobile can still be driven by the internal combustion engine using a quantity of fuel remaining in the fuel tank.
The display elements 12, 20, 28, 30, 32 each comprise at least one light-emitting element for adjusting a display brightness for the respective display elements 12, 20, 28, 30, 32. In order to create agreeable brightness conditions for the driver of the automobile, the respective display brightness is adjusted by the relevant light-emitting element such that the display elements 12, 20, 28, 30, 32 have at least substantially the same display brightnesses.
The display apparatus 10 (combination instrument) also comprises a sensing device, not visible in FIG. 1, having at least one sensing element 38 for sensing an ambient brightness for surroundings of the display elements 12, 20, 28, 30, 32.
In this case, the method for operating the display apparatus 10 involves the respective display brightness being adjusted on the basis of the sensed ambient brightness. In other words, the respective display brightness can be adjusted by the respective light-emitting element on the basis of the sensed ambient brightness. By way of example, the sensing element 38 is a photodiode or a phototransistor.
The display apparatus 10 also comprises an operating element 40, which is in the form of a pushbutton in the present case. Pushing of the operating element 40, for example by the driver of the automobile, allows a function of the automobile and—in the present case—of the display apparatus 10 to be prompted. In the present case, this function is that operation, i.e. pushing of the operating element 40, adjusts a value for an odometer reading for the automobile to 0. The odometer reading is what is known as a daily odometer reading, which indicates a distance in kilometers that the automobile has covered since the operating element 40 was last operated. In other words, the odometer reading can be adjusted to 0 by the mechanical operating element 40.
The use of the mechanical operating element 40 to prompt this function requires both development and manufacture of the operating element 40, which results in relatively high costs for the display apparatus 10.
DE 100 21 101 B4 discloses a display apparatus in a vehicle, wherein a large number of pieces of information can be displayed in the display apparatus. The display apparatus is lit by differently colored light sources, particularly cold-cathode fluorescent lamps. The display apparatus contains a liquid crystal cell, with the differently colored light sources being able to be actuated by a control unit. The control unit can sense and evaluate at least one trip parameter of the vehicle, with a brightness of the differently colored light source being able to be altered by the control unit on the basis of the trip parameter. In this case, the liquid crystal cell can be backlit by the differently colored light sources.
In addition, DE 35 01 594 U1 discloses a cockpit instrument for motor vehicles for displaying speed and/or boost pressure and/or engine speed and/or fuel display and/or oil pressure and/or oil temperature and/or alternator voltage and/or battery charge state or the like with a housing that is closed by a front panel and that contains a measuring element. In this case, provision is made for the front panel to have a plurality of light-emitting diodes of the same type secured to or on it in a linear arrangement with respect to one another.